I installed Debian on a USB flash drive on my QNAP TS-419p+(Kirkwood)
inserted into the lowest backside USB port.Everything's been working
very smoothly until I tried to connect my printer to the NAS (also via
USB). Via SSH the NAS reacted with the same error to every command as
soon as the printer was connected:

-bash: /bin/dmesg: Input/output error

Upon manual power off (button on the NAS) and reboot, the system took a
very long time to come up and finally booted. Since then, the system
boots quickly againbut I don't know how to get my printer working.